One of the driving forces behind imperialism was Social Darwinism. This social theory was based on the belief that

That individuals, groups, and peoples are subject to the same Darwinian laws of natural selection as plants and animals. For example, WASP- white, Anglo-Saxon protestants believed themselves to be superior to black or even other white people like Jews. So, they thought they were the "fittest" and deserved to be at the top of the social hierarchy.

Explanation:

answer; (a) he was a u.s senator for 38 years;